Position detection device having magnetoresistive element

ABSTRACT

A magnetoresistive element is provided with a plurality of magnetoresistive laminated bodies arranged in an array and a plurality of lead electrodes that electrically connect the plurality of magnetoresistive laminated bodies in series. A first lead electrode electrically connected to a first surface in the lamination direction of a first magnetoresistive laminated body among the plurality of magnetoresistive laminated bodies and a second lead electrode electrically connected to a first surface in the lamination direction of a second magnetoresistive laminated body adjacent in the series direction are electrically connected without a magnetoresistive laminated body being interposed in between.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is based on Japanese Patent Application No.2016-195442 filed on Oct. 3, 2016, the disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a magnetoresistive element and a methodof manufacturing such, along with a position detection device having themagnetoresistive element.

BACKGROUND

Conventionally, position detection devices have been used to detect theposition and amount of movement (amount of change) through therotational movement or linear movement of a moving body, in machinetools and the like. As this kind of position detection device, a devicehas been known that is provided with a magnetic sensor capable ofdetecting change in an external magnetic field accompanying movement ofthe moving body, and a signal indicating the relative positionalrelationship between the moving body and a magnetic sensor is outputfrom the magnetic sensor.

As the magnetic sensor used in such a position detection device, asensor that is a laminated body having a free layer and a magnetizationfixed layer and provided with a magnetoresistive element (TMR element)in which resistance varies with a change in the magnetization directionof the free layer in accordance with an external magnetic field isknown.

The TMR element includes a plurality of magnetoresistive laminatedbodies (TMR laminated bodies) connected in series. The TMR laminatedbodies have low electrostatic discharge (ESD) tolerance, and there is arisk that the TMR laminated bodies could be destroyed if excess voltageor excess current caused by a surge in static electricity or the likeflows. Consequently, a plurality of TMR laminated bodies is connected inseries in the TMR element for the purposes of reducing the voltageapplied to each of the TMR laminated bodies and to improve ESDtolerance.

PRIOR ART Patent Literature

[PATENT LITERATURE 1] JP Laid-Open Patent Application No. 2009-260164.

SUMMARY Problem to be Solved by the Invention

Each TMR laminated body in the above-described TMR element is designedso that the shape when viewed from above or below the laminationdirection is circular. By making the shape of the TMR laminated bodiescircular, it is possible to cause the magnetization direction of thefree layer to change linearly accompanying changes in the externalmagnetic field, so it is possible to show stable change in resistance,making highly precise position detection by the magnetic sensorpossible. However, there are cases in which distortion occurs in theshape of each of the TMR laminated bodies due to errors or the like whenmanufacturing the TMR laminated bodies. The problem exists that harmonicdistortion is included in the signal waveform output from the magneticsensor, originating from distortion of the shape of each of the TMRlaminated bodies, in particular, the shape of the free layer. Inparticular, as equipment provided with magnetic sensors has become morecompact and more highly functional, detecting the position of the movingbody with higher precision has been sought, creating circumstances inwhich even minute detection errors caused by slight distortion of theshape of the above-described TMR laminated bodies cannot be ignored.

In order to correct the harmonic distortion, even if an attempt is madeto correct the distortion of the shape of each TMR laminated body, thecorrection amount is a slight amount that is less than the measurementlimit in the measuring length SEM or the like, so it is extremelydifficult to manage this correction amount In addition, for example, ina typical resistor that is manufactured through a method such as screenprinting or the like, in order to get the resistance value to match thedesigned value, a laser trimming process is accomplished by irradiatinga laser on the resistor while monitoring the resistance value of themanufactured resistor. However, even if the attempt is made to correctdistortion of the shape of each of the TMR laminated bodies byaccomplishing the laser trimming process of irradiating a laser on eachof the TMR laminated bodies, there is a risk that the film structure ofthe TMR laminated bodies could be destroyed by the laser beingirradiated.

In consideration of the above-described problems, it is an object of thepresent invention to provide a magnetoresistive element in whichharmonic distortion caused by distortion of the shape of eachmagnetoresistive laminated body due to manufacturing errors or the likecan be corrected and which can show stable changes in resistance valueaccompanying changes in the external magnetic field, a method ofmanufacturing such, and a position detection device including such amagnetoresistive element

Means for Solving the Problem

In order to resolve the above-described problems, the present inventionprovides a magnetoresistive element comprising a plurality ofmagnetoresistive laminated bodies arranged in an array, and a pluralityof lead electrodes that electrically connect the plurality ofmagnetoresistive laminated bodies in series; wherein the plurality ofmagnetoresistive laminated bodies includes a first magnetoresistivelaminated body and a second magnetoresistive laminated body, which isadjacent in the series direction to the first magnetoresistive laminatedbody. The plurality of lead electrodes includes a first lead electrode,which is electrically connected to a first surface in the laminationdirection of the first magnetoresistive laminated body, and a secondlead electrode, which is electrically connected to the first surface inthe lamination direction of the second magnetoresistive laminated bodyand positioned substantially coplanar with the first lead electrode. Thefirst lead electrode and the second lead electrode are electricallyconnected without the magnetoresistive laminated body being interposedin between (Invention 1).

In the above-described invention (Invention 1), at least one electrodeconnection lead that directly connects at least two lead electrodesamong the plurality of lead electrodes is further provided, and thefirst lead electrode and the second lead electrode are preferablyconnected via the electrode connection lead (Invention 2).

In the above-described invention (Invention 1), in a planar view from afirst surface side of the magnetoresistive laminated body, at least oneof the magnetoresistive laminated bodies included in the plurality ofmagnetoresistive laminated bodies preferably has a shape and/or sizediffering from the other magnetoresistive laminated bodies (Invention3). Preferably at least one of the magnetoresistive laminated bodies hasa substantially elliptical shape, and the other magnetoresistivelaminated bodies have substantially circular shapes (Invention 4).Preferably the size of at least one of the magnetoresistive laminatedbodies is at least 1.5 times larger than the sizes of the othermagnetoresistive laminated bodies (Invention 5).

In the above-described invention (Invention 1), it is possible to use aTMR laminated body as the magnetoresistive laminated body.

In addition, the present invention provides a position detection devicecomprising a magnetic sensor unit that outputs a sensor signal based onchanges in an external magnetic field accompanying movements of a movingbody, and a position detection unit that detects the position of themoving body based on the sensor signal output from the magnetic sensorunit. The magnetic sensor unit includes the magnetoresistive elementaccording to the above-described invention (Invention 1) (Invention 7).

In the above-described invention (Invention 7), it is preferred that themoving body is a rotating moving body that rotationally moves about aprescribed axis of rotation and that the position detection unit detectsthe rotational position of the rotating moving body based on the sensorsignal output from the magnetic sensor unit (Invention 8).

Furthermore, the present invention provides a manufacturing method for amagnetoresistive element including a process for forming a plurality ofbottom lead electrodes, a process for forming a magnetoresistivelaminated body in a portion of the magnetoresistive laminated bodyformation regions among a plurality of magnetoresistive laminated bodyformation regions set in each of the plurality of bottom leadelectrodes, a process for forming a measurement lead on each top surfaceof at least two of the magnetoresistive laminated bodies, a process forapplying an electric current on the magnetoresistive laminated bodiesvia the measurement lead, and measuring resistance value changes in themagnetoresistive laminated bodies accompanying changes in an externalmagnetic field, a process for forming magnetoresistive laminated bodiesin regions where magnetoresistive laminated bodies are not formed, amongthe plurality of magnetoresistive laminated body formation regions,based on the measurement results of the resistance value changes, and aprocess for forming a plurality of top lead electrodes that connect themagnetoresistive laminated bodies in series (Invention 9).

In the above-described invention (Invention 9), it is preferable thatthe method further includes a process for finding the change in acorrection-use resistance value in order to correct the resistance valuechange that has been measured, and that a magnetoresistive laminatedbody is formed in a region where a magnetoresistive laminated body hasnot been formed, among the plurality of magnetoresistive laminated bodyformation regions, based on change in the correction-use resistancevalue (Invention 10).

Efficacy of the Invention

With the present invention, it is possible to provide a magnetoresistiveelement in which harmonic distortion caused by distortion of the shapeof each magnetoresistive laminated body due to manufacturing errors orthe like can be corrected and which can show stable changes inresistance value accompanying changes in the external magnetic field, amethod of manufacturing such, and a position detection device includingsuch a magnetoresistive element

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a schematic configuration of amagnetoresistive element according to a preferred embodiment of thepresent invention.

FIG. 2 is a cross-sectional view showing a schematic configuration of amagnetoresistive laminated body in the preferred embodiment of thepresent invention.

FIG. 3 is a plan view showing the schematic configuration of theprincipal sections of the magnetoresistive laminated body in thepreferred embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a schematic configuration ofthe principal sections of the magnetoresistive element according to thepreferred embodiment of the present invention.

FIGS. 5A˜5D are procedure flow diagrams showing, in cut end views, themanufacturing procedures for the magnetoresistive element according tothe preferred embodiment of the present invention.

FIGS. 6A˜6C are procedure flow diagrams showing, in cut end views,procedures following FIG. 5D, among the manufacturing procedures for themagnetoresistive element according to the preferred embodiment of thepresent invention.

FIG. 7 is a graph showing an ideal waveform for resistance value changesin the magnetoresistive element according to the preferred embodiment ofthe present invention, the waveform of resistance value changes in themain TMR laminated body and the waveform of resistance value changes inthe correction-use TMR laminated body.

FIG. 8 is a perspective view showing a schematic configuration of aposition detection device in the preferred embodiment of the presentinvention.

FIG. 9 is a block diagram showing a schematic configuration of amagnetic sensor in the preferred embodiment of the present invention.

FIG. 10 is a circuit diagram schematically showing the circuitconfiguration of a first magnetic sensor unit in the preferredembodiment of the present invention.

FIG. 11 is a circuit diagram schematically showing the circuitconfiguration of a second magnetic sensor unit in the preferredembodiment of the present invention.

FIG. 12 is a cross-sectional view showing the schematic configuration ofthe principal sections of the magnetoresistive element according toanother embodiment of the present invention.

DETAILED DESCRIPTION

A preferred embodiment of the present invention will be described withreference to the drawings. FIG. 1 is a perspective view showing aschematic configuration of a magnetoresistive element according to apreferred embodiment of the present invention, FIG. 2 is across-sectional view showing a schematic configuration of amagnetoresistive laminated body in the preferred embodiment of thepresent invention, FIG. 3 is a plan view showing a schematicconfiguration of the principal sections of the magnetoresistivelaminated body in the preferred embodiment of the present invention, andFIG. 4 is a cross-sectional view showing a schematic configuration ofthe principal sections of the magnetoresistive element according to thepreferred embodiment of the present invention.

As shown in FIGS. 1˜4, a magnetoresistive element 1 according to thepreferred embodiment is provided with a plurality of magnetoresistivelaminated bodies 2 arranged in an array and a plurality of leadelectrodes 3 that electrically connect the plurality of magnetoresistivelaminated bodies 2 in series.

Specifically, the magnetoresistive element 1 has a plurality of bottomlead electrodes 31, a plurality of magnetoresistive laminated bodies 2,and a plurality of top lead electrodes 32. The bottom lead electrodes 31and the top lead electrodes 32 are, for example, configured by one typeof conductive material among Cu, Al, Au, Ta, Ti or the like or acomposite film of two or more of such conductive materials, and thethickness of each is 0.3˜2.0 μm.

The plurality of bottom lead electrodes 31 is provided on a substrate(undepicted). Each of the plurality of bottom lead electrodes 31 has along, slender, roughly rectangular shape and is provided so there is aprescribed gap between any two adjacent bottom lead electrodes 31 in theelectrical series direction of the plurality of magnetoresistivelaminated bodies 2 arranged in an array. Near each of the two ends inthe lengthwise direction of the bottom lead electrodes 31, themagnetoresistive laminated bodies 2 are provided. That is, twomagnetoresistive laminated bodies 2 are provided on top of each of theplurality of bottom lead electrodes 31.

The magnetoresistive laminated bodies 2 in the preferred embodiment areTMR elements, and, as shown in FIG. 2, include a magnetization fixedlayer 22 in which the magnetization direction has been fixed, a freelayer 24 in which the magnetization direction changes in accordance withthe direction of the applied magnetic field, a non-magnetic layer 23positioned between the magnetization fixed layer 22 and the free layer24, and an antiferromagnetic layer 21.

The magnetoresistive laminated body 2 has a configuration in which thefree layer 24, the non-magnetic layer 23, the magnetization fixed layer22 and the antiferromagnetic layer 21 are laminated in that order fromthe bottom lead electrode 31 side. The free layer is electricallyconnected to the bottom lead electrode 31, and the antiferromagneticlayer 21 is electrically connected to the top lead electrode 32. As thematerial configuring the free layer 24 and the magnetization fixed layer22, for example, NiFe, CoFe, CoFeB, CoFeNi, Co₂MnSi, Co₂MnGe, FeOX(oxides of Fe) or the like can be used. The thickness of the free layer24 and the magnetization fixed layer 22 is around 1˜10 nm each.

The non-magnetic layer 23 is a tunnel barrier layer, and is a requiredfilm in order to cause the tunnel magnetoresistive effect (TMR) effectto be expressed in the magnetoresistive laminated body 2 of thepreferred embodiment. As materials configuring the non-magnetic layer23, Cu, Au, Ag, Zn, Ga, TiO_(X), ZnO, InO, SnO, GaN, ITO (Indium TinOxide), Al₂O₃, MgO or the like can be used. The non-magnetic layer 23may be configured by a laminated film of two or more layers. Forexample, the non-magnetic layer 23 can be configured by a three-layerlaminated film of Cu/ZnO/Cu, or a three-layer laminated film ofCu/ZnO/Zn, in which one of the Cu is replaced with Zn. The thickness ofthe non-magnetic layer 23 is around 0.1˜5 nm.

The antiferromagnetic layer 21 is configured by an antiferromagneticmaterial containing Mn and at least one type of element selected fromthe group of Pt, Ru, Rh, Pd, Ni, Cu, Ir, Cr and Fe, for example. The Mncontent in this antiferromagnetic material is, for example, around35˜95%. The antiferromagnetic layer 21 configured by thisantiferromagnetic material serves the role of fixing the direction ofmagnetization of the magnetization fixed layer 22, through exchangecoupling with the magnetization fixed layer 22.

A plurality of top lead electrodes 32 is provided on the plurality ofmagnetoresistive laminated bodies 2. Each top lead electrode 32 has along, slender, roughly rectangular shape. The top lead electrode 32 ispositioned so that a prescribed gap exists between two adjacent top leadelectrodes 32 in the electrical series direction of the plurality ofmagnetoresistive laminated bodies 2 arranged in an array and so that theplurality of magnetoresistive laminated bodies 2 are connected inseries, and the top lead electrode 32 electrically connects theantiferromagnetic layers 21 of the adjacent two magnetoresistivelaminated bodies to each other. The magnetoresistive laminated body 2may have a configuration in which the antiferromagnetic layer 21, themagnetization fixed layer 22, the non-magnetic layer 23 and the freelayer 24 are sequentially layered from the bottom lead electrode 31side. In addition, there may be a cap layer (protective layer) betweenthe free layer 24 and the bottom lead electrode 31 or the top leadelectrode 32.

In the magnetoresistive laminated bodies 2 in the embodiment, theresistance value changes in accordance with the angle formed by themagnetization direction of the free layer 24 with respect to themagnetization direction of the magnetization fixed layer 22, and theresistance value becomes a minimum when the angle is 0° (themagnetization directions are parallel) and the resistance value becomesa maximum at 180° (the magnetization directions are antiparallel).

As shown in FIG. 3, the plurality of magnetoresistive laminated bodies 2arranged in an array in the magnetoresistive element 1 in the preferredembodiment contains a magnetoresistive laminated body 2 a, the shape ofwhich, when viewed from the top side (the top lead electrode 32 side) inthe direction of lamination of the magnetoresistive laminated body 2, issubstantially circular, and a magnetoresistive laminated body 2 b with asubstantially elliptical shape that differs from that of themagnetoresistive laminated body 2 a In FIG. 3, the depiction of the toplead electrode 32 is omitted. In the preferred embodiment, themagnetoresistive laminated body 2 a having the substantially circularshape at times will be referred to as the main TMR laminated body, andthe magnetoresistive laminated body 2 b having the substantiallyelliptical shape will at times be referred to as the correction-use TMRlaminated body.

As described below, during manufacturing procedures for themagnetoresistive element 1 according to the preferred embodiment,changes in the resistance value accompanying changes in the externalmagnetic field are measured. In this resistance value change, harmonicdistortion originating from manufacturing errors in the main TMRlaminated body 2 a (distortion in the shape of the main TMR laminatedbody 2 a) are included. In the magnetoresistive element 1, it is idealfor the waveform exhibiting this change in resistance value to be a sinewave or a cosine wave. However, when harmonic distortion is included inthis resistance value change, the waveform exhibiting this resistancevalue change deviates from the ideal sine wave or cosine wave. Themagnetoresistive element 1 according to the preferred embodiment is suchthat by including the correction-use TMR laminated body 2 b in order tomake the waveform exhibiting the resistance value change approach theideal sine wave or cosine wave, harmonic distortion included in theresistance value change of the magnetoresistive element 1 is corrected,and it is possible to make the waveform exhibiting the resistance valuechange of the magnetoresistive element 1 approach the ideal sine wave orcosine wave.

The shape and size of the correction-use TMR laminated body 2 b are ashape and size capable of correcting the harmonic distortion originatingfrom manufacturing errors or the like in the main TMR laminated body 2 a(distortion in the shape of the main TMR laminated body 2 a). Forexample, the shape of the correction-use TMR laminated body 2 b may besubstantially elliptical, differing from the substantially circularshape of the main TMR laminated body 2 a. In addition, the size of thecorrection-use TMR laminated body 2 b may be 1.5 times larger than thesize of the main TMR laminated body 2 a, and preferably 2˜10 times. Forexample, the size of the main TMR laminated body 2 a is around 1˜2 μm,and the size of the correction-use TMR laminated body 2 b is around1.5˜20 μm. The size of the magnetoresistive laminated body 2 refers tothe diameter of the top surface when the shape is a circular shape whenviewed from the top side (the top lead electrode 32 side) in thelamination direction of the magnetoresistive laminated body 2 and refersto the major axis of the top surface when the shape is an ellipticalshape.

In the magnetoresistive element 1 according to the preferred embodiment,among the plurality of magnetoresistive laminated bodies 2 arranged inan array, at least an adjacent pair of the first magnetoresistivelaminated body 211 and second laminated body 212 are electricallyconnected via a direct connection between a first lead electrode 321,which is connected to the top surface (antiferromagnetic layer 21) inthe direction of lamination of the first magnetoresistive laminated body211, and a second lead electrode 322, which is connected to the topsurface (antiferromagnetic layer 21) in the direction of lamination ofthe second magnetoresistive laminated body 212 (see FIG. 4). The firstmagnetoresistive laminated body 211 in the preferred embodiment is acorrection-use TMR laminated body 2 b, and the second magnetoresistivelaminated body 212 is a main TMR laminated body 2 a adjacent to thecorrection-use TMR laminated body 2 b in the series direction of themagnetoresistive laminated body 2.

As shown in FIG. 4, the first lead electrode 321 and the second leadelectrode 322 are positioned substantially on the same plane and aredirectly connected. In other words, the first lead electrode 321 and thesecond lead electrode 322 are electrically connected without themagnetoresistive laminated body 2 interposed between, and the mutuallydirectly connected first lead electrode 321 and second lead electrode322 can configure the top lead electrode 32 that electrically connectsthe first magnetoresistive laminated body 211 and the secondmagnetoresistive laminated body 212. The fact that first lead electrode321 and the second lead electrode 322 are positioned on substantiallythe same plane means that the second lead electrode 322 and a section321 b of the first lead electrode 321, other than a section 321 a thatoverlaps the second lead electrode 322, are positioned on the sameplane.

As described below, the magnetoresistive element 1 according to thepreferred embodiment is manufactured by forming a correction-use TMRlaminated body 2 b that measures the resistance value changeaccompanying changes in the external magnetic field during themanufacturing process and corrects the difference when there is adifference between the waveform indicating the resistance value changeand the ideal sine wave or cosine wave. The second lead electrode 322 isa measurement lead electrode 33 used to measure the resistance valuechange accompanying changes in the external magnetic field.

In this manner, after the above-described resistance value change ismeasured via the measurement lead electrode 33 (second lead electrode322), the correction-use TMR laminated body 2 b is formed, and all ofthe magnetoresistive laminated bodies 2 including the correction-use TMRlaminated body 2 b are connected in series. Consequently, in themagnetoresistive element 1 according to the preferred embodiment, thereis at least one location where the first lead electrode 321 and thesecond lead electrode 322 are directly connected.

In the bottom lead electrode 31 where the correction-use TMR laminatedbody 2 b is formed, a conductive layer 4 made of a conductive materialis provided, and on the top surface of the conductive layer 4, anelectrode pad 5 made of Au or the like is provided.

A method of manufacturing the magnetoresistive element 1 having theabove-described configuration will be described. FIGS. 5A˜5D and FIGS.6A˜6C are process flow charts showing manufacturing procedures for themagnetoresistive element 1 according to the preferred embodiment incross sectional views.

On a semiconductor substrate 60, a first conductive material film isformed through sputtering or the like, and a plurality of bottom leadelectrodes 31 is formed through a photolithography process (see FIG.5A). Further, between the bottom lead electrodes 31, an insulating layer(omitted from drawing) is provided.

Next, a magnetoresistive film (a laminated film in which a ferromagneticfilm, a nonmagnetic film, a ferromagnetic film and an antiferromagneticfilm are sequentially layered) 20 is formed through sputtering or thelike to cover the plurality of bottom lead electrodes 31 (see FIG. 5B),and the main TMR laminated body 2 a is formed in a prescribed region ineach of the plurality of bottom lead electrodes 31 through aphotolithography process (see FIG. 5C).

The prescribed region where the correction-use TMR laminated body 2 b isformed is covered by the magnetoresistive film 20. In the preferredembodiment, a state in which one correction-use TMR laminated body 2 bis formed on each of two bottom lead electrodes 31 is used as anexample, but this is intended to be illustrative and not limiting, andit would be fine to form one correction-use TMR laminated body 2 b onone bottom lead electrode 31 or to form three or more correction-use TMRlaminated bodies 2 b.

Next, a second conductive material film is formed through sputtering orthe like on the plurality of main TMR laminated bodies 2 a formed on thebottom lead electrodes 31, and top lead electrodes 32 and measurementlead electrodes 33 that connect in series the plurality of main TMRlaminated bodies 2 a are formed through a photolithography process (seeFIG. 5D).

Furthermore, in the plurality of main TMR laminated bodies 2 a connectedin series by the bottom lead electrodes 31, the top lead electrodes 32and the measurement lead electrodes 33, the resistance value changeaccompanying changes in external magnetic field are measured. Thisresistance value change is measured for example using a Quasi StaticTest (QST) device (WLA-3000, made by Integral Solutions Int'l), or thelike.

When the waveform indicating the resistance value change measured inthis way has a difference from an ideal sine wave or cosine wave, acorrection resistance value change required by the correction-use TMRlaminated body 2 b to correct this difference is found. The resistancevalue change in the magnetoresistive element 1 is expressed by the totalof the resistance value change measured above (the resistance valuechange in the main TMR laminated body 2 a) and the resistance valuechange in the correction-use TMR laminated body 2 b. Consequently, thecorrection resistance value change required by the correction-use TMRlaminated body 2 b is found from the difference between the resistancevalue change in the main TMR laminated body 2 a and the ideal resistancevalue change, so that the waveform indicating the resistance valuechange in the magnetoresistive element 1 approaches the idea sine waveor cosine wave.

For example, when a magnetoresistive element 1 including 50magnetoresistive laminated bodies 2 is manufactured, first, forty-sevenmain TMR laminated bodies 2 a are manufactured. The resistance valuechange in these forty-seven main TMR laminated bodies 2 a accompanyingchanges in the external magnetic field is measured, and a waveform WF2 ashown in FIG. 7 is obtained. FIG. 7 is a graph showing the idealwaveform WFI for resistance value change, a waveform WF2 a of resistancevalue change in the main TMR laminated bodies 2 a, and a waveform WF2 bof resistance value change in the correction-use TMR laminated bodies inthe magnetoresistive element 1 according to the preferred embodiment. InFIG. 7, the vertical axis indicates resistance value R (Ω), and thehorizontal axis indicates the angle of rotation θ (deg). This waveformWF2 a has prescribed differences from the ideal sine wave WFI. In thiscase, the waveform WF2 b of correction resistance value change requiredby the correction-use TMR laminated bodies 2 b to correct thesedifferences is found. The waveform WF2 b of correction resistance valuechanges is found by subtracting the waveform WF2 a from the waveformWFI. In this manner, it is possible to find the correction resistancevalue changes required by the correction-use TMR laminated bodies 2 b.

Correction of the resistance value changes in the plurality of main TMRlaminated bodies 2 a is accomplished only by adding the resistance valuechange in the correction-use TMR laminated bodies 2 b to this resistancevalue change. That is to say, correction cannot be done by subtractingthe resistance value from the resistance value change in the pluralityof main TMR laminated bodies 2 a. Depending on the extent ofmanufacturing errors (distortion in the shape of the main TMR laminatedbodies 2 a) arising in the main TMR laminated bodies 2 a, cases mayarise in which correction of the resistance value changes are difficultor impossible with only one correction-use TMR laminated body 2 b.Hence, the number of correction-use TMR laminated bodies 2 b in theplurality of magnetoresistive laminated bodies 2 included in themagnetoresistive element 1 may be determined after grasping in advancethe extent of manufacturing errors or the like arising in the main TMRlaminated bodies 2 a.

On the other hand, when the number of correction-use TMR laminatedbodies 2 b in the plurality of magnetoresistive laminated bodies 2 istoo large, harmonic distortions originating from manufacturing errorsarising in the correction-use TMR laminated bodies 2 b (distortions fromthe design shape of the correction-use TMR laminated bodies 2 b) arise.Consequently, the number of correction-use TMR laminated bodies 2 b ispreferably determined by considering the extent of manufacturing errorsarising in the main TMR laminated bodies 2 a and the extent ofmanufacturing errors arising in the correction-use TMR laminated bodies2 b. For example, when fifty magnetoresistive laminated bodies 2 areincluded in the magnetoresistive element 1, preferably 1˜4, or morepreferably 2˜4, correction-use TMR laminated bodies 2 b are formed.

Furthermore, the size and shape of the correction-use TMR laminatedbodies 2 b are designed based on the correction resistance value change.When the difference between the resistance value change in the main TMRlaminated bodies 2 a and the ideal sine wave or cosine wave issubstantially zero, magnetoresistive laminated bodies 2 of the same sizeand shape as the plurality of main TMR laminated bodies 2 a are formedwithout forming correction-use TMR laminated bodies 2 b in thepredetermined regions for forming correction-use TMR laminated bodies 2b on the bottom lead electrode 31.

Next, based on the above-described design, the correction-use TMRlaminated bodies 2 b are formed through a photolithography process (seeFIG. 6A). The correction-use TMR laminated bodies 2 b have shapes andsizes differing markedly from the main TMR laminated bodies 2 a Forexample, the shape of the main TMR laminated bodies 2 a is substantiallycircular, while the shape of the correction-use TMR laminated bodies 2 bis elliptical with the major axis facing the short direction of thebottom lead electrode 31. The design of the shape and size of thecorrection-use TMR laminated bodies 2 b is determined in themanufacturing processes of the magnetoresistive element 1 based on theresistance value change in the main TMR laminated bodies 2 a, so it isimpossible to prepare in advance the reticle or the like for forming thecorrection-use TMR laminated bodies 2 b. Hence, the correction-use TMRlaminated bodies 2 b are formed, for example, through a photolithographyprocess using the pattern formation technology of electron beamlithography or multiple exposure using the reticle used when forming theplurality of main TMR laminated bodies 2 a.

Then, the top lead electrodes 32 are formed on the top surface of thecorrection-use TMR laminated bodies 2 b, and all of the magnetoresistivelaminated bodies 2 including the correction-use TMR laminated bodies 2 bare connected in series (see FIG. 6B). At this time, because themeasurement lead electrodes 33 are formed in the magnetoresistivelaminated bodies 2 (main TMR laminated bodies 2 a) adjacent to thecorrection-use TMR laminated bodies 2 b, the top lead electrodes 32formed on the top surface of the correction-use TMR laminated bodies 2 band the measurement lead electrodes 33 are directly connected. Finally,the conductive layer 4 and the electrode pad 5 are formed on the bottomlead electrode 31 (see FIG. 6C). In this manner, the magnetoresistiveelement 1 according to the preferred embodiment is formed.

As discussed above, with the magnetoresistive element 1 according to thepreferred embodiment, harmonic distortion originating from manufacturingerrors or the like in the plurality of main TMR laminated bodies 2 aincluded in the magnetoresistive element 1 are corrected by thecorrection-use TMR laminated bodies 2 b, so it is possible to show astable resistance value change accompanying changes in the externalmagnetic field. Accordingly, by using the magnetoresistive element 1according to the preferred embodiment as one configuration element in aposition detection device that detects the position of a moving body, itis possible to markedly improve position detection precision in theposition detection device.

Next, a position detection device using the magnetoresistive element 1according to the preferred embodiment will be described. FIG. 8 is aperspective view showing a schematic configuration of a positiondetection device in the preferred embodiment, FIG. 9 is a block diagramshowing a schematic configuration of a magnetic sensor in the preferredembodiment, FIG. 10 is a circuit diagram schematically showing thecircuit configuration of a first magnetic sensor unit in the preferredembodiment, and FIG. 11 is a circuit diagram schematically showing thecircuit configuration of a second magnetic sensor unit in the preferredembodiment.

As shown in FIG. 8, a position detection device 100 according to thepreferred embodiment is provided with a magnetic sensor 110 and a movingbody 120 capable of moving relative to the magnetic sensor 110. In thepreferred embodiment, an example is described in which a rotary encoderprovided with a rotating moving body 120 that rotates about a prescribedrotational axis is used as the position detection device 100, but thisis intended to be illustrative and not limiting, and a rotary encoder orthe like provided with a moving body 120 that moves linearly relative toa prescribed direction with respect the magnetic sensor 110 would befine. In the state shown in FIG. 8, the rotating moving body 120 is arotary magnet in which N poles and S poles are alternatingly magnetizedabout the outer perimeter.

As shown in FIG. 9, the magnetic sensor 110 includes a first magneticsensor unit 111 and a second magnetic sensor unit 112 that output sensorsignals based on changes in the external magnetic field accompanyingrotational movement of the rotating moving body 120, and a calculator113 that calculates the rotational angle θ of the rotating moving body120 based on the sensor signals output from the first and secondmagnetic sensor units 111 and 112.

The calculator 113 contains an A/D (analog/digital) converter 114, whichconverts analog signals (sensor signals) output from the first andsecond magnetic sensor units 111 and 112 into digital signals, and anarithmetic processor 115, which does arithmetic processing on thedigital signals digitally converted by the A/D converter 114 andcalculates the rotation angle θ.

The first and second magnetic sensor units 111 and 112 each contain atleast one magnetic detection element and may contain a pair of magneticdetection elements connected in series. In this case, the first andsecond magnetic sensor units 111 and 112 each have a Wheatstone bridgecontaining a pair of magnetic detection elements connected in series.

As shown in FIG. 10, a Wheatstone bridge circuit 111 a of the firstmagnetic sensor unit 111 has a power source port V1, a ground port G1,two output ports E11 and E12, a first pair of magnetic detectionelements R11 and R12 connected in series, and a second pair of magneticdetection elements R13 and R14 connected in series. One end of each ofthe magnetic detection elements R11 and R13 is connected to the powersource port V1. The other end of the magnetic detection element R11 isconnected to one end of the magnetic detection element R12 and theoutput port E11. The other end of the magnetic detection element R13 isconnected to one end of the magnetic detection element R14 and theoutput port E12. The other end of each of the magnetic detectionelements R12 and R14 is connected to the ground port G1. A power sourcevoltage of a prescribed magnitude is applied to the power source portV1, and the ground port G1 is connected to ground.

As shown in FIG. 11, a Wheatstone bridge circuit 112 a of the secondmagnetic sensor unit 112 has the same configuration as the Wheatstonebridge circuit 111 a of the first magnetic sensor unit 111 and containsa power source port V2, a ground port G2, two output ports E21 and E22,a first pair of magnetic detection elements R21 and R22 connected inseries, and a second pair of magnetic detection elements R23 and R24connected in series. One end of each of the magnetic detection elementsR21 and R23 is connected to the power source port V2. The other end ofthe magnetic detection element R21 is connected to one end of themagnetic detection element R22 and the output port E21. The other end ofthe magnetic detection element R23 is connected to one end of themagnetic detection element R24 and the output port E22. The other end ofeach of the magnetic detection elements R22 and R24 is connected to theground port G2. A power source voltage of a prescribed magnitude isapplied to the power source port V2, and the ground port G2 is connectedto ground.

In the preferred embodiment, the magnetoresistive element 1 according tothe preferred embodiment (see FIGS. 1˜4) is used as all of the magneticdetection elements R11˜R14 and R21˜R24 contained in the Wheatstonebridge circuits 111 a and 112 a.

In FIG. 10 and FIG. 11, the magnetization directions of themagnetization fixed layers 22 of the magnetic detection elements R11˜R14and R21˜R24 are indicated by the filled-in arrows. In the first magneticsensor unit 111, the magnetization directions of the magnetizationfixing layers 22 of the magnetic detection elements R11˜R14 are parallelto a first direction D1, and the magnetization directions of themagnetization fixed layers 22 of the magnetic detection elements R11 andR14, and the magnetization direction of the magnetization fixed layers22 of the magnetic detection elements R12 and R13, are mutuallyantiparallel directions. In addition, in the second magnetic sensor unit112, the magnetization directions of the magnetization fixed layers 22of the magnetic detection elements R21˜R24 are parallel to a seconddirection orthogonal to the first direction, and the magnetizationdirections of the magnetization fixed layers 22 of the magneticdetection elements R21 and R24, and the magnetization direction of themagnetization fixed layers 22 of the magnetic detection elements R22 andR23, are mutually antiparallel. In the first and second magnetic sensorunits 111 and 112, the potential differences between the output portsE11 and E12 and the output ports E21 and E22 change in accordance withchanges in the direction of the magnetic field accompanying rotationalmovement of the rotating moving body 120, and first and second sensorsignals S1 and S2 are output to the calculator 113 as signals indicatingmagnetic field strength.

A difference detector 116 outputs a signal corresponding to the electricpotential difference between the output ports E11 and E12 to the A/Dconverter 114 as the first sensor signal S1. A difference detector 117outputs a signal corresponding to the electric potential differencebetween the output ports E21 and E22 to the A/D converter 114 as thesecond sensor signal S2.

As shown in FIG. 10 and FIG. 11, the magnetization direction of themagnetization fixed layers 22 of the magnetic detection elements R11˜R14in the first magnetic sensor unit 111 and the magnetization direction ofthe magnetization fixed layers 22 of the magnetic detection elementsR21˜R24 in the second magnetic sensor unit 112 are mutually orthogonal.In this case, the waveform of the first sensor signal S1 is a cosinewave dependent on the rotational angle θ, and the waveform of the secondsensor signal S2 is a sine wave dependent on the rotational angle θ. Inthe preferred embodiment, the phase of the second sensor signal S2differs by one quarter of a signal period, that is to say π/2 (90°),relative to the phase of the first sensor signal S1.

The A/D converter 114 converts the first and second sensor signals(analog signals related to the rotational angle θ) S1 and S2 output fromthe first and second magnetic sensor units 111 and 112 into digitalsignals, and these digital signals are input into the arithmeticprocessor 115.

The arithmetic processor 115 does arithmetic processing on the digitalsignals converted from analog signals by the A/D converter 114, andcalculates the rotational angle θ of the rotating moving body 120. Thearithmetic processor 115 is configured by a microcomputer or the like,for example.

The rotational angle θ of the rotating moving body 120 is calculated byan arctangent computation such as that indicated by the below equation,for example.θ=atan(S1/S2)

Within a 360° range, there are two solutions differing by 180° for therotational angle θ in the above equation. However, by thepositive/negative combination of the first sensor signal S1 and thesecond sensor signal S2, it is possible to determine which of the twosolutions to the above equation is the true value of the rotationalangle θ. That is to say, when the first sensor signal S1 has a positivevalue, the rotational angle θ is larger than 0° and smaller than 180°.When the first sensor signal S1 has a negative value, the rotationalangle θ is larger than 180° and smaller than 360°. When the secondsensor signal S2 has a positive value, the rotational angle θ is in therange larger than 0° and smaller than 90° or larger than 270° andsmaller than 360°. When the second sensor signal S2 has a negativevalue, the rotational angle θ is larger than 90° and smaller than 270°.The arithmetic processor 115 calculates the rotational angle θ withinthe 360° range based on the above equation and a determination of thepositive/negative combination of the first sensor signal S1 and thesecond sensor signal S2.

In the position detection device 100 in the preferred embodiment havingthe above-described configuration, when the external magnetic fieldchanges accompanying rotational movement of the rotating moving body120, the resistance values of the magnetic detection elements R11˜R14and R21˜R24 of the first and second magnetic sensor unit 111 and 112change in accordance with the change in that external magnetic field,and the first and second sensor signals S1 and S2 are output from thedifference detectors 116 and 117 in accordance with the electricpotential difference of the respective output ports E11, E12, E21 andE22 of the first magnetic sensor unit 111 and second magnetic sensorunit 112. Then, the first sensor signal S1 and the second sensor signalS2 output from the difference detectors 116 and 117 are converted intodigital signals by the A/D converter 114. Following this, the rotationalangle θ of the rotating moving body 120 is calculated by the arithmeticprocessor 115.

In the position detection device 100 in the preferred embodiment, themagnetic detection elements R11˜R14 and R21˜R24 (magnetoresistiveelements 1) of the first and second magnetic sensor units 111 and 112can contain correction-use TMR laminated bodies 2 b, so it is possibleto exhibit a stable resistance value change accompanying changes in theexternal magnetic field. Hence, with the position detection device 100in the preferred embodiment, it is possible to detect the rotationalangle θ of the rotating moving body 120 with high precision.

The preferred embodiment described above was described to facilitateunderstanding of the present invention, and is not intended to limit thepresent invention. Accordingly, the various elements disclosed in theabove-described preferred embodiment should be construed to include alldesign changes and equivalents falling within the technical scope of thepresent invention.

In the above-described preferred embodiment, a state in which adjacenttop lead electrodes 32 were directly connected to each other was used asan example, but the present invention is not limited to such a state.For example, as shown in FIG. 12, adjacent top lead electrodes 32 may beconnected to each other via an electrode connection lead 34. Inaddition, adjacent bottom lead electrodes 31 may be connected to eachother directly or via the electrode connection lead 34.

In the above-described preferred embodiment, a state in which theWheatstone bridge circuits 111 a and 112 a contained in the first andsecond magnetic sensor units 111 and 112 are full bridge circuitscontaining a first pair of magnetic detection elements R11, R12, R21 andR22 connected in series and a second pair of magnetic detection elementsR13, R14, R23 and R24 connected in series was used as an example, butthe present invention is not limited to such a state. For example, theseWheatstone bridge circuits 111 a and 112 a may be half bridge circuitscontaining a first pair of magnetic detection elements R11, R12, R21 andR22 connected in series.

DESCRIPTION OF REFERENCE SYMBOLS

-   1. Magnetoresistive element-   2. Magnetoresistive laminated body    -   2 a. Main TMR laminated body    -   2 b. Correction-use TMR laminated body-   3. Lead electrode    -   31. Bottom lead electrode    -   32. Top lead electrode        -   321. First lead electrode        -   322. Second lead electrode    -   33. Measurement lead electrode    -   34. Electrode connection lead

What is claimed is:
 1. A position detection device comprising: amagnetic sensor unit that outputs a sensor signal based on changes in anexternal magnetic field accompanying movements of a moving body; and aposition detection unit that detects the position of the moving body,based on the sensor signal output from the magnetic sensor unit, whereinthe magnetic sensor unit includes a magnetoresistive element, themagnetoresistive element comprises a plurality of magnetoresistivelaminated bodies arranged in an array and a plurality of lead electrodesthat electrically connect the plurality of magnetoresistive laminatedbodies in series, the plurality of magnetoresistive laminated bodiesincludes a first magnetoresistive laminated body and a secondmagnetoresistive laminated body, which is adjacent in the seriesdirection to the first magnetoresistive laminated body, the plurality oflead electrodes includes a first lead electrode, which is electricallyconnected to a first surface in the lamination direction of the firstmagnetoresistive laminated body, and a second lead electrode, which iselectrically connected to the first surface in the lamination directionof the second magnetoresistive laminated body and positionedsubstantially coplanar with the first lead electrode, and the first leadelectrode and the second lead electrode are electrically connectedwithout the magnetoresistive body being interposed between the firstlead electrode and the second lead electrode.
 2. The position detectiondevice according to claim 1, wherein: the moving body is a rotatingmoving body that rotationally moves about a prescribed axis of rotation;and the position detection unit detects the rotational position of therotating moving body based on the sensor signal output from the magneticsensor unit.
 3. The position detection device according to claim 1,wherein: the magnetoresistive element further comprises at least oneelectrode connection lead that directly connects at least two leadelectrodes among the plurality of lead electrodes, and the first leadelectrode and the second lead electrode are connected via the electrodeconnection lead.
 4. The position detection device according to claim 1,wherein when viewed along the lamination direction of themagnetoresistive laminated body, at least one of the magnetoresistivelaminated bodies included in the plurality of magnetoresistive laminatedbodies has a shape and/or size differing from the other magnetoresistivelaminated bodies.
 5. The position detection device according to claim 4,wherein in a planar view from a first surface side of themagnetoresistive laminated body, at least one of the magnetoresistivelaminated bodies has a substantially elliptical shape, and the othermagnetoresistive laminated bodies have substantially circular shapes. 6.The position detection device according to claim 4, wherein in a planarview from a first surface side of the magnetoresistive laminated body,the size of at least one of the magnetoresistive laminated bodies is atleast 1.5 times larger than the sizes of the other magnetoresistivelaminated bodies.
 7. The position detection device according to claim 1,wherein the magnetoresistive laminated bodies are TMR laminated bodies.